Recently, fibromyalgia diagnosis has been based on the modified American College of Rheumatology Preliminary Diagnostic Criteria for fibromyalgia. To assist with diagnosis, recent evidence shows that compared to healthy people, people with fibromyalgia present with differences on functional MRI (fMRI) whole brain scans, as well as differences in a functional blood biomarker challenge test, known as fm/a. The fm/a determines the function of the immune system in response to a stimulus, and has been used previously to show that people with fibromyalgia have a severely blunted immune response.